The present invention relates to a low temperature infrared radiation source.
Use of an infrared source to provide a radiation source which essentially matched the radiation of the source to the throughput radiation of an interferometer spectrometer is known. For example, U.S. Pat. No. 4,724,329 discloses an infrared source which is composed of a radiating element positioned at the center of a hollow, inwardly reflecting sphere having a single aperture positioned to fill the entrance field of view of a spectrometer with infrared radiation. This infrared source is, however, contained in the disclosed interferometer and does not function as a remote source. Further, the temperatures present in this source are undesirably high, particularly if the device is to be located in an area in which significant amounts of volatile, ignitable materials are present.
U.S. Pat. No. 4,681,445 also discloses an interferometer in which a radiation source is incorporated. The details of this radiation source are not given but it is clear from the disclosure that use of the radiation source external to the interferometer was not contemplated.
U.S. Pat. No. 4,740,082 also discloses a spectrophotometer in which an infrared radiation source beam is employed. In this disclosure, it is taught that the source beam may be positioned within the enclosure of a spectrophotometry instrument or external to the instrument. This disclosure does not, however, teach a specific instrument which employs an infrared source external to the device. The radiation source employed is a heated wire which provides radiation between the wavelengths of 5000 and 50 wavenumbers in the infrared spectrum. Such heated wire could not, however, be used as an external remote infrared source in an area where volatile materials might be present in significant quantities without substantial risk of fire or explosion.
In view of the greater flexibility of a remote source spectrophotometer, it would be advantageous to have an infrared radiation source which is external to the spectrophotometer that did not generate temperatures which would preclude its use in areas where volatile chemicals might be present in significant quantities.